Simultaneously scouring and bleaching with chlorite



I Patented Aug 19, 1941 SIMULTANEOUSLY SCOURING AND BLEACH- ING WITH CHLORITE Archie Louis Dubeau, Niagara Falls, N. Y., as-

signor to The Mathieson Alkali Works, Inc., New York, N. Y., a corporation of Virginia No Drawing. Application December 24, 1938, Serial No. 247,637

. v 7 Claims.

This invention is concerned with textile treatment and provides an improved method for bleaching and scouring fabrics of vegetable origin. The invention finds particular application in the treatment of unfinished fabrics containing a large proportion of cellulosic fibres, such for example, as greige cloth or similar unfinished fabrics containing cotton, fiax, hemp, jute, and the like.

Greige cloth and similar newly woven fabrics have very limited use. For most purposes, they must be subjected to further treatment to place them in saleable form because (1) the natural color bodies occurring in the vegetable fibres detract from the appearance of the fabric; (2) they contain varying amounts of motes (i e., non-,

fibrous particles such as cottonseed fragments) that adhere to the fibres throughout the spinning and weaving processes; and (3) the presence of natural waxes and pectins and of sizings, principally starchy, (which are' applied to the warp threads during weaving) makes the fabric water-repellent and thus tends to interfere with bleaching or dyeing. Removal of these various impurities from the fabrics so as to render them whiteand absorbent frequently involves a long and extensive series of treatments, and in general the'more delicate and finer fabrics (which will not withstand the action of strong hot a1- kalis) require the longer and more complex treatments. Thus, certain cloths, including cotton and rayon mixtures. used extensively in corset cloth and draperies, spun rayon and spun rayon mixtures, yarn dyed fabrics such as marquisette with colored dots and shirting with colored stripes, velveteen and corduroy, usually are subjected to a mild, long and complex treatment in such equipment as Rodney-Hunt kettles, becks, jigs, and the like. Such complex treatments are exemplified by that in a Rodney-Hunt kettle which, for a heavy cloth, involves the following series of operations:

In accordance with my invention, the above enumerated series of operations is simplified and shortened to the end that substantial savings in time, laborp equipment and reagents are realized and the clothsuffers less deterioration than in heretofore customary practice. As a result of my investigations, I have discovered that the impurities such as motes, wax, pectins, natural color bodies and sizings in unfinished cloth may be removed advantageously and simultaneously by subjecting the cloth to the action of a solution of sodium chlorite in the presence of acid and of a detergent such, for example, as a sulphated or sulphonated fatty alcohol which exerts its detergent action in the presence of the acid and is not substantially decomposed by the sodium chlorite present. Thus, in accordance with my in-' vention, greige cloth and the like is simultaneously bleached and secured by subjecting it to the action of an acid aqueous solution of sodium chlorite which contains a suitable detergent such, for example, as sulphated lauryl alcohol. The operation preferably is carried on in a Rodney- Hunt kettle or similar apparatus. If mote removal is particularly difiicult, as for example,

when the cloth contains an abnormally high proportion of motes, pretreatment of the cloth with caustic is advantageous. However, in most instances, no pretreatment is necessary and the operation simply involves-exposing the cloth to the action of a hot aqueous solution containing sodium chlorite, acid and a suitable detergent, and subsequently to a water wash.

In commercial operations, the particular treatment conditions will depend upon the weight per unit area of the cloth which is to be processed, the amount and kind of sizings applied to the cloth during weaving, the size and proportion of motes present in the cloth and the quality desired in the finished product. The following large scale practice, however, exemplifies conditions which have been found to be generally appropriate.

In this operation the apparatus employed was a Rodney-Hunt kettle and the fabric comprised 700 yards of cotton 'greige corset cloth (rayon stripe fancy) 2 yards of which weighed 1 pound.

This cloth was treated as it came from the weaving operation as follows:

A sodium chlorite solution was made up in the kettle by dissolving 3 pounds of commercial sodium chlorite in 300 gallons'of water. The

cloth was loaded into this solution which was then brought to a temperature of approximately 180 F. To the hot solution was added two quarts of 28% (by weight) of acetic acid and 1 pound of a synthetic detergent known as "Gardinol," consisting substantially of sodium lauryl sulphate. The treatment in the presence of the detergent, the acid and the sodium chlorite was continued for 4 hours at a temperature of about 180 F., after which the cloth was given a water wash and then dried. The cloth was satisfactory in all respects. It had good absorbency, the sizing, wax and pectins originally present in the cloth having been substantially removed. Moreover, motes had been completely removed and the cloth was well bleached.

As indicated hereinbefore, caustic pretreatment is beneficial when the cloth contains an abnormally high proportion of motes. This caustic pretreatment may be accomplished by padding a 6 or 7% (by weight) cold aqueous solution of caustic soda on the cloth and then stacking it for several hours, usually over-night. Contact with the cold solution for this length of time softens the motes and facilitates their complete removal in the subsequent treatment with sodium chlorite. Pretreatment thus decreases the amount of time necessary for the subsequent scouring and bleaching, so that a two-hour treatment in the above-described solution of sodium chlorite, acetic acid and sulphated lauryl alcohol usually is sufficient, even with very heavy cloths, and results in a material of superior whiteness, satisfactory absorbency both as to degree and distribution, a low residual starch content and complete removal of motes.

The concentration of sodium chlorite to employ depends upon the kind and amount of impurities in the cloth, the weight of the cloth and the degree of impurity removal desired. Generally speaking, however, good results may be obtained with an aqueous solution to which has been added from .5 gram per liter to 2.0 grams per liter of sodium chlorite, although the available chlorine maybe as low as .1 gram per liter or as high as 6 grams per liter, measured as sodium chlorite.

The temperature of the solution is also dependent upon the kind and amount of impurities present and the degree of removal required. Bleaching and scouring are, however, accelerated by relatively high temperatures, and in order to accomplish these operations in relatively short time, the temperature of the solution should range from about 160 F. to the boiling point of the solution at atmospheric pressure. The operation may well be conducted by immersing the cloth into sodium chlorite solution while it is at room temperature, thereafter heating the solution to the required degree and then adding the acid and the detergent,

In general, the concentration of acid to be employed should be low. The solution, however, should at all times have a definitely acid reaction (1. e., a pH below 7) and good results are obtained when the solution has a hydrogen ion concentration (pH) ranging from 3 to 5. Any acid may be employed to obtain such hydrogen ion concentration, but I prefer to employ weak acids such as acetic acid, lactic acid, formic acid or phosphoric acid.

The detergent to be employed must exert its detergent action in the presence of the acid and must be resistant to decomposition under the oxidizing influence of sodium chlorite. Many synthetic detergents are suitable among them being:

A secondary aliphatic alcohol suliate, in which R and R represent hydrocarbon groups.

CHPNCHr-COR Hr-SOsNB a fatty acid amide m which n represents a hydrocarbon group.

CHiCOOIi HgSOzNa A fatty acid ester, in which it represents a. hydrocarbon group.

Sodium sulioethylmethyllauramide.

Sodium sulioethyl myristate.-.-

Sodium diamyl suliosuccinata... CIIICOOR' NaSO: HCOOR A sulionated succinic acid ester,

in which R and R represent hydrocarbon groups.

An alkylated aromatic sulionate.

RSO|N8DD aliphatic sulionate in which it represents a hydrocarbon group.

Sodium decyl benzene sulionate Sodium hexudecyl sullonate There is nothing particularly critical about the proportions of detergent to employ except that enough should be employed to emulsify the impurities removed from the cloth. Hence, the proportion will depend upon the particular detergent, the amount of impurities to be removed. and the speed with which removal is to be accomplished. Generally speaking, about to 1 pound of detergent per gallons of water will be satisfactory.

My invention is applicable to the treatment of any cellulosic fabrics which require bleaching or scouring, but offers particular advantages in the treatment of delicate fabrics which will not withstand strong hot alkalis. These advantages are:

(1) Economy of time. In most instances the time for bleaching and securing may be cut approximately in half.

(2) Better removal of starch and other sizings from the cloth because the sodium chlorite exerts a strong solubilizing action upon the starch.

(3) Creases and similar causes of uneven dyeing are avoided.

(4) Action of the sodium chlorite in the acid solution, even at elevated temperatures, has no degrading effect upon cellulosic fibres. Tests for oxy-cellulose conducted upon cloth processed in accordance with my invention are negative and loss in tensile strength of such fabric is too low to be measured.

I claim:

1. In the treatment of unfinished cellulosic fabrics, the improvement which comprises simultaneously bleaching and scouring the unfinished fabric by subjecting the fabric to the action of an aqueous acid solution containing sodium presence of the acid and is substantially unoxidized by the sodium chlorite, said detergent being selected from the group consisting of aliphatic alcohol sulphates, sulphonated fatty acid amides,

,sulphonated fatty acid esters, sulphonated suc- ""cinic acid esters, alkylated aromatic sulphonates.

and aliphatic sulphonates.

2. In the treatment of an unfinished cellulosic fabric, the improvement which comprises simultaneously bleaching and scouring the unfinished fabric by subjecting the fabric to the action of sodium chlorite in an acid aqueous solution having a pH ranging from about 3 to about 5 and which contains a detergent that is active in the presence of the acid and is resistant to decomposition by the sodium chlorite, said detergent being selected from the group consisting of aliphatic alcohol sulphates, sulphonated fatty acid amides, suiphonated fatty acid esters, sulphonated succinic acid esters, alkylated aromatic sulphonates, and. aliphatic sulphonates.

3. In the treatment of an unfinished cellulosic fabric, the improvement which comprises simultaneously bleaching and scouring the unfinished fabric by subjecting the fabric to the action of sodium chlorite in an acid aqueous solution containing sodium chlorite in proportions ranging from about 0.1 gram per liter to about 6 grams .per liter and also containing a detergent that is active in the presence of the acid and is resistant to oxidation by the sodium chlorite, said being selected from the group consisting of allphatic alcohol sulphates, sulphonated fatty acid amides, sulphonated fatty acid esters, sulphonated succinic acid esters, alkylated aromatic sulphonates, and aliphatic sulphonates.

5. In the treatment of an unfinished cellulosic fabric the improvement which comprises simultaneously bleaching and scouring the unfinished fabric by subjecting the fabric to the action of a boiling acid aqueous solution containing sodium chlorite and a detergent that is active in the presence of the acid andis'stable-int'he presence 7 of the acid and the sodium chlorite, said detergent being selected from the group consisting of aliphatic alcohol sulphates, sulphonated fatty 'acid amides, suiphonated fatty acid esters, sulphonated succinic acid esters, alkylated aromatic sulphonates, and aliphatic sulphonates.

6. In the treatment of an unfinished cellulosic fabric containing motes, the improvement which comprises subjecting the fabric to pretreatment with an aqueous caustic solution for a substantial period of time in a relatively cold condition and thereafter subjecting the fabric to the action of a hot acid aqueous solution containing sodium chlorite and a detergent that is active inthe presence of the acid and is substantially undecomposed by the sodium chlorite,. whereby the detergent being selected from the group consisting of aliphatic alcohol sulphates, sulphonated fatty acid amides, sulphonated fatty acid esters,

sulphonated succinic acid esters, alkylatedaromatic sulphonates, and aliphatic sulphonates.

4. In the treatment of an unfinished cellulosic fabric, the improvement which comprises simultaneously bleaching and securing the unfinished fabric by subjecting the fabric to the action of a notacid aqueous solution containing sodium unfinished fabric is bleached and scoured simultaneously, said detergent being selected from the group consisting of aliphatic alcohol sulphates,

sulphonated fatty acid amides, sulphonated fatty acid esters, sulphonated succinic acid esters, alkylated aromatic sulphonates, and aliphatic sulphonates.

7. In the treatment of unfinished cellulosic fabrics, the improvement which comprises simulchlorite and a detergent that is active in the.

presence of the acid and is resistant to decomposition by the sodium chlorite, said detergent taneously bleaching and scouring the unfinished fabric by subjecting the fabric to the action of an aqueous acid solution containing sodium chlorite and a detergent which is active in the presence of the acid and is substantially unoxidized by the sodium chlorite, said detergent comprising an aliphatic alcohol sulphate.

ARCHIE LOUIS DUBEAU.' 

